1. Field of the Invention
The invention relates to a positive crankcase ventilation (PCV) device for internal combustion engines. More specifically, the invention relates to an improved oil drain device having a dedicated path for blow-by gases that is separate from a fluid path for oil removed from crankcase gases.
2. Description of the Related Art
An internal combustion engine typically includes a combustion chamber, where a fuel air mixture is burned to cause movement of a set of reciprocating pistons, and a crankcase, which contains the crankshaft driven by the pistons. During operation, it is normal for the engine to experience “blow-by,” wherein combustion gases leak past the pistons from the combustion chamber and into the crankshaft. These combustion or blow-by gases contain moisture, acids and other undesired by-products of the combustion process.
An engine typically includes a Positive Crankcase Ventilation (PCV) system for removing harmful gases from the engine and prevents those gases from being expelled into the atmosphere. The PCV system does this by using manifold vacuum to draw vapors from the crankcase into the intake manifold. Vapor is then carried with the fuel/air mixture into an intake manifold of the combustion chambers where it is burned. Generally, the flow or circulation within the system is controlled by the PCV valve, which acts as both a crankcase ventilation system and as a pollution control device.
It is normal for blow-by gases to also include a very fine oil mist. The oil mist is carried by the PCV system to the manifold. The oil mist is then burned in the combustion chamber along with the fuel/air mixture. This results in an increase in oil consumption. A known method of removing oil from the blow-by gases is to use a labyrinth, punched-hole impact plate (PIP) or cyclone-type separator design. A path is provided through which small oil droplets pass and collects into larger droplets. The droplets are then re-introduced back to a sump via a drain device. The sump generally holds excess oil in the system. Examples of oil separators are disclosed in U.S. Pat. Nos. 6,279,556 B1 and 6,626,163 B1 to Busen et al., both of which are assigned to Walter Hengst GmbH & Co. KG.
Conventional oil drain devices have a single passage for both blowby gases and oil. The blowby gas is driven to the manifold by a pressure difference between the manifold and sump, while the oil is driven by gravity to the sump. The flow of blow-by gas hinders or prevents this flow of oil to the sump.
Thus, it remains desirable to provide an improved oil drain device that minimizes disturbance of the oil moving between the oil separator and the sump by the blow-by gases.